As a creation method of a power system configuration, it is proposed to decide a network configuration by a genetic algorithm in consideration of restrictions in the capacity of a feeder like "Optimization Method of Power Distribution System Configuration by Genetic Algorithm" (pp. 591 to 598) described in Journal of Institute of Electrical Engineers of Japan, Vol. C116, No. 5. According to the method, to maintain the radial network, the gene structure of the genetic algorithm is made appropriate and when a loop system or dividing system is set due to crossing-over or. mutation, a countermeasure is taken individually.